Positive cartridge indexing device



March 12, 1963 A. L. MONTANA POSITIVE CARTRIDGE INDEXING DEVICE 2 Sheets-Sheet 1 Filed Dec. 14, 1960 IN V EN TOR. AHTEEL LMU rfitmu arch 12, 1963 A. L. MONTANA 3,

POSITIVE CARTRIDGE INDEXING DEVICE Filed Dec. 14, 1960 2 Sheets-Sheet 2 &

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INVENTOR. Alfrefl L- Mnlflurnl tnt filice 39 Patented Mar. 12, 1963 3,030,793 POSITIVE CARTRIDGE INDEXING DEVICE Alfred L. Montana, East Longmeadow, Mass, assignor to the United States of America as represented by the Secretary of the Army Filed Dec. 24, 1960, Ser. No. 75,891 1 Claim. (Cl. 89-33) (Granted under Title 35, US. Code (1952), see. 266) advancing a cartridge belt into the firearm receiver and index successive ones of the cartridges in the belt for pickup by a reciprocating bolt during counter-recoil travel to battery position.

One of the means for feeding cartridge belts to a firearm having a reciprocating bolt includes transversely actuated feeding pawls which sequentially advance the cartridges in the belt to a feed throat for pickup by the bolt during counterrecoil travel to battery position. With such a device it is necessary to provide holding pawls for securely indexing the cartridges in position for pickup by the bolt after the cartridges are delivered to the indexed position by the feeding pawl.

In some firearms, because of the particular structure of the cartridge belt links, the holding pawls are con tactable with the indexed cartridge on a diameter which is less than the maximum diameter. Consequently, be-

cause the holding pawls must be laterally spaced sufficiently to permit the passage of the indexed cartridge therebetween when stripped from the retaining link by the bolt, the indexed cartridge is loosely positioned between the holding pawls. As a result, the indexed cartridge is free to vibrate between contacts with the holding pawls and this permits the next linked cartridge in the belt to be also displaceable against the associated one of the holding pawls for a pivotal displacement thereof. Therefore, the holding pawl on the feeding side of the indexed cartridge is sometimes displaced sufficiently to permit displacement of such cartridge to the extent that it cannot be contacted by the bolt during counterrecoil travel.

It is, therefore, an object of this invention to provide for such a feeding mechanism having a pair of cooperating holding pawls a device for securing the holding pawls against pivotal displacement when a cartridge is indexed therebetween.

It is another object of this invention to provide such a mechanism which is readily installed in conventional feeding mechanisms and which is rugged in construction and positive in its functions.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. 1 is a longitudinally cross-sectioned view of a firearm with the bolt adjacent the position for stripping a cartridge from its link during counterrecoil travel;

FIG. 2 is a view taken along line 2-2 of FIG. 1;

FIG. 3 is a view taken along line 3-3 of FIG. 1;

FIG. 4 is a view taken along line 4-4 of FIG. 1;

FIG. 5 is a view similar to FIG. 4 but showing the position of the retainer relative to the holding pawls when the cartridge belt is advanced during the feeding portion of the operating cycle of the bolt; and

FIG. 6 is an enlarged exploded perspective view of the retainer.

Shown in the figures is a gun 12 having a receiver 14 with a bolt 16 slidingly disposed therein for longitudinal displacement and a barrel 18 provided with a chamber for receiving a cartridge 20 for discharge. A plurality of cartridges 20 are each gripped by a link 22 which links are joined to form a belt 24. A feeding mechanism 26 is provided in receiver 14 to sequentially pull belt 24 thereinto and position successive ones of the cartridges therein for pickup by bolt 16 during recoil travel thereof.

Feeding mechanism 26 includes a feed tray '28 which is transversely disposed across the top of receiver 14 rearwardly of the breech end of barrel 18. Feed tray 28 slidingly supports belt 24 for passing cartridges 20 there in to a central feed throat 30 in the feed tray for pickup by bolt 16 during counterrecoil travel and slidingly passes links 22 from gun 12 after the cartridges are stripped therefrom. Feed tray 28 has a cover 32 pivotally mounted on receiver 14 and such cover is provided with a lateral recess 34 across the underside to slidingly receive a feed slide 36 which reciprocates over the feed tray normal to the longitudinal axis of gun 12. Feed slide 36 is actuated for reciprocation by conventional cam and lever means 37 operationally disposed between the feed slide 36 and bolt 1.6.

Feed slide 36 carries a pivotal feed pawl 33 which extends angularly downward, coincident with a plane normal to the longitudinal axis of gun 12, so as to ride over the leading cartridge 20 in belt 24 during travel of feed slide 36 away from feed throat 30". Thus, feed pawl 38 is positioned in back of the leading cartridge 26 for displacement thereof to the feed throat when feed slide 36 is actuated towards feed throat 30. Cam and lever means 37 are arranged so as to advance belt 24 during the final portion of the recoil travel of bolt 16, after the fired case of the cartridge is extracted from barrel 18, and to return feed pawl 38 to engage the next cartridge during the initial portion of the counterrecoil travel of the bolt. Thus, feed slide 36 is at rest relative to feed tray 28 during the ramming and extraction of a cartridge 29 by bolt 16.

A pair of holding pawls 40 are pivotally mounted on cover 32 so as to be positioned on opposite sides of feed throat 39 when the cover is closed and the holding pawls are spring-biased to holding positions wherein each extends downwardly and towards the feed throat. Holding pawls 40 are similar in configuration and are similariy mounted on cover 32 to permit alternate feeding of belt 24 from either side of receiver 14. The holding pawl 40 on the side of feed throat 31 from which the empty links 22 are ejected serves to stop the leading cartridge delivered by feed pawl 33 over the feed throat. The holding pawl 41 on the side of feed throat 39 from which belt 24 is fed is arranged to be pivoted upwardly by the leading cartridge 26 in the belt during advancement of the leading cartridge to the feed throat and then, when such cartridge is positioned thereover, pivots downwardly in back thereof. Thereby, belt 2 is blocked against excessive backward displacement and leading cartridge 26 therein is indexed over feed throat 31 As best shown in F168. 1 and 3, holding pawls 41 are positioned to be contactable with the index cartridge 26 forwardly of link 22 at the reduced diameter portion of the cartridge case and, when the holding pawls are in the holding position, the ends of the holding pawls are spaced sufiiciently to permit passage of the largest diameter portion of the case therethrough.

To prevent pivotal displacement of holding pawls 40, while a cartridge 20 is indexed therebetween, there is provided a retainer 42 which is slidingly supported by a bottomed hole 44 which extends longitudinally forward into cover 32 from the front side of recess 34 and approximately central thereof. Retainer 42 includes a shaft portion 46 having the same cross-sectional dimensions 3 as hole 44 so as to be slidingly received thereby. A cross bar 43 is fixed to the underside of shaft portion 46 and is arranged so as to be contactable with the upper sides of the holding pawls 49, when in their normal holding positions, to block displacement therefrom. Extending rearwardly from shaft portion 46 is a lug 56 which has sliding contact with the front face of feed slide 36. Lug 5d and cross bar 48 are so arranged that, when the lug is in contact with the front face of feed slide 36, the cross bar is forwardly disposed relative to holding pawl: 40 and away from contact therewith.

Retainer 42 is biased into resilient contact with feed slide 36 by a spring 52 which is received by an axial well 54- extending rearwardly into cylindrical portion 46 from the front end thereof and a mating recess 56 extending forwardly into cover 32 from the end of hole 44.

Provided in the front side of feed slide 36 is a recessed cut 58 having a ramp 66 which extends forwardly and outwardly. from the front face of the feed slide and which is positioned so as to be contactable by lug 50 when the feed slide is positioned for picking up cartridge 20 succeeding the indexed cartridge and is at rest pending the stripping thereof by bolt 16. Whereby, through the bias of spring 52 and the clearance provided by recess cut 53, retainer 42 is actuated rearwardly to move cross bar 48 over holding pawls 40 after leading cartridge 20 is indexed therebetween.

According to conventional design, feed slide 36 is st"- 'tionary while an indexed cartridge 26 is stripped from 'belt 24 by bolt 16 and chambered thereby in barrel 18 and, therefore, cross bar 48 remains in blocking position over feed pawls t!) to assure positive indexing of the cartridge. When chambered cartridge 20 is fired and bolt 16 is recoiled, feed slide 36, which was actuated to position feed pawl 38 thereon in back of the next cartridge in belt 24 during the preceding counterrecoil travel of the bolt, is actuated by the bolt to draw the engaged cartridge to feed throat Zifiready for pickup by the bolt during subsequent counterrecoil travel thereof. When the engaged cartridge 20 is indexed over feed throat30 during recoil travel of bolt 16, holding pawls 40 extend downwardly on opposite sides of the cartridge which is blocked thereby in indexed position when feed pawl 38 immediately moves away from the cartridge during the counterrecoil travel of the bolt. Feed slide 36 reaches its outward pickup position-prior to the engagement of bolt 16 with the indexed cartridge and, therefore, re cessed cut 58 is in registry with lug to permit rearward displacement of retainer 42 by spring 52. Thereby, cross bar 48 is positioned over holding pawls 40 when the indexed cartridge is being stripped from belt 24 and chambered in barrel 18 to assure positive indexing of the cartridge.

From. the foregoing it is readily seen that there is provided herein a device which positively indexes a cartridge while being transferred from a cartridge belt into the chamber of a barrel and which is simple and rugged in construction and positive in its functions.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claim isintended to include such variations. a

I claim:

In a firearm provided with a feed slide carrying a feed.

pawl for sequentially advancing cartridges to a feed throat, the combination including holding pawl means .disposed adjacent the feed throat for indexingv thereat cartridge is indexed by said holding pawl means at the feed throat.

References Cited in the file ofthis patent- UNITED STATES PATENTS 2,899,865 Colby Aug. 18, 1959 

